execute all examples in gallery and prettify printed info

[StrikerRUS]

By executing all examples regardless they have plots or not, we make sure they are runnable and up-to-date.

By default, Sphinx-Gallery will parse and add all files with a .py extension to the gallery, but only execute files beginning with plot_. https://sphinx-gallery.github.io/stable/configuration.html#parsing-and-executing-examples-via-matching-patterns